From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57484) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WmOhZ-0001Zb-95 for qemu-devel@nongnu.org; Mon, 19 May 2014 10:38:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WmOhQ-0001Mf-Ui for qemu-devel@nongnu.org; Mon, 19 May 2014 10:38:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45679) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WmOhQ-0001Mb-Nv for qemu-devel@nongnu.org; Mon, 19 May 2014 10:37:56 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s4JEbtgn008792 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Mon, 19 May 2014 10:37:55 -0400 Date: Mon, 19 May 2014 16:37:52 +0200 From: Kevin Wolf Message-ID: <20140519143752.GC4060@noname.redhat.com> References: <1399858555-9672-1-git-send-email-famz@redhat.com> <1399858555-9672-4-git-send-email-famz@redhat.com> <87d2f9q2pi.fsf@blackfin.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87d2f9q2pi.fsf@blackfin.pond.sub.org> Subject: Re: [Qemu-devel] [PATCH v19 03/16] block: Introduce op_blockers to BlockDriverState List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: Fam Zheng , jcody@redhat.com, hbrock@redhat.com, qemu-devel@nongnu.org, rjones@redhat.com, imain@redhat.com, stefanha@redhat.com, pbonzini@redhat.com Am 19.05.2014 um 16:10 hat Markus Armbruster geschrieben: > Fam Zheng writes: > > > BlockDriverState.op_blockers is an array of lists with BLOCK_OP_TYPE_MAX > > elements. Each list is a list of blockers of an operation type > > (BlockOpType), that marks this BDS as currently blocked for a certain > > type of operation with reason errors stored in the list. The rule of > > usage is: > > > > * BDS user who wants to take an operation should check if there's any > > blocker of the type with bdrv_op_is_blocked(). > > > > * BDS user who wants to block certain types of operation, should call > > bdrv_op_block (or bdrv_op_block_all to block all types of operations, > > which is similar to the existing bdrv_set_in_use()). > > > > * A blocker is only referenced by op_blockers, so the lifecycle is > > managed by caller, and shouldn't be lost until unblock, so typically > > a caller does these: > > > > - Allocate a blocker with error_setg or similar, call bdrv_op_block() > > to block some operations. > > - Hold the blocker, do his job. > > - Unblock operations that it blocked, with the same reason pointer > > passed to bdrv_op_unblock(). > > - Release the blocker with error_free(). > > > > Signed-off-by: Fam Zheng > > Reviewed-by: Benoit Canet > > Reviewed-by: Jeff Cody > > --- > > block.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++ > > include/block/block.h | 7 +++++ > > include/block/block_int.h | 5 ++++ > > 3 files changed, 87 insertions(+) > > > > diff --git a/block.c b/block.c > > index b749d31..32338ca 100644 > > --- a/block.c > > +++ b/block.c > > @@ -335,6 +335,7 @@ void bdrv_register(BlockDriver *bdrv) > > BlockDriverState *bdrv_new(const char *device_name, Error **errp) > > { > > BlockDriverState *bs; > > + int i; > > > > if (bdrv_find(device_name)) { > > error_setg(errp, "Device with id '%s' already exists", > > @@ -353,6 +354,9 @@ BlockDriverState *bdrv_new(const char *device_name, Error **errp) > > if (device_name[0] != '\0') { > > QTAILQ_INSERT_TAIL(&bdrv_states, bs, device_list); > > } > > + for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { > > + QLIST_INIT(&bs->op_blockers[i]); > > + } > > bdrv_iostatus_disable(bs); > > notifier_list_init(&bs->close_notifiers); > > notifier_with_return_list_init(&bs->before_write_notifiers); > > @@ -1907,6 +1911,8 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest, > > pstrcpy(bs_dest->device_name, sizeof(bs_dest->device_name), > > bs_src->device_name); > > bs_dest->device_list = bs_src->device_list; > > + memcpy(bs_dest->op_blockers, bs_src->op_blockers, > > + sizeof(bs_dest->op_blockers)); > > } > > > > /* > > @@ -5269,6 +5275,75 @@ void bdrv_unref(BlockDriverState *bs) > > } > > } > > > > +struct BdrvOpBlocker { > > + Error *reason; > > + QLIST_ENTRY(BdrvOpBlocker) list; > > +}; > > + > > +bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp) > > +{ > > + BdrvOpBlocker *blocker; > > + assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); > > Space between cast and its operand is unusual. Please don't respin just > for that. That was a surprising statement for me. Do you have an idea how to grep for casts? I tried '*)' just in order to find _some_ examples of casts, and there doesn't seem to be a clear winner. But if there is one, it appears to be the version with space. (I won't reject patches with either style.) Kevin